Yellowing English Boxwood Hedge

Asked March 14, 2013, 10:24 AM EDT

We have an English Box Wood hedge that outlines our lawn and walkway. It has been planted for about 10-years and is kept trimmed regularly. However, it has a yellow tint to it and I would like a spray application to resolve this issue. When we planted them we laid down a weed barrier that seems to keep any fertilizer applied at the plant’s drip line not to be of any benefit.

Washington County Oregon

4 Responses

Thank you for your question to Ask the Expert.

Yellowing of leaves is a common sign of nitrogen deficiency, particularly on the older leaves on the plant. If you have been applying granular fertilizer at the drip line, that material should dissolve with the rains and make its way into the soil, but it might be leaching during the winter and not accessible by the plants.

At this time, you could try using a water-soluble fertilizer in liquid form, which should be added slowly to the root zone of the plants such that it soaks through the weed fabric. Follow the directions on the package in terms of the amount to add. If you see an rapid re-greening of the leaves, then it is likely that your plants are experiencing a nitrogen deficiency.

One of the disadvantages of weed barrier is that organic matter from the leaves dropping does not make its way into the soil and contribute toward mineralization of nutrients for use by the plant.

Please let me know if you have any further questions.

Weston

What liquid form water-soluble fertilizer would you recommend? Also, do you apply it to the entire shrub or just on the top of the plant it’s self? I was considering applying Bonide’s Liquid Iron. What are your thoughts?
I sure appreciate you help with this issue.

What liquid form water-soluble fertilizer would you recommend? Also, do you apply it to the entire shrub or just on the top of the plant it’s self? I was considering applying Bonide’s Liquid Iron. What are your thoughts? I sure appreciate you help with this issue.

For liquid, water-soluble fertilizer, you will want to look for products that say something like "mix with water" and provide directions for how to make a soil drench such that you can water your boxwood hedge and the solution will make its way through the landscape fabric. More is not better. Follow the instructions in terms of the rate of application indicated for landscape shrubs. Unless you are seeing green veins on the leaves and yellow between the veins (symptoms of iron deficiency), then the iron product that you have is probably not necessary.

Please let me know if you have any further questions.

Weston